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Biomedical subjects

Y Naka

Publications and source records attributed to Y Naka.

At least 109 records · Page 6Linked to original sources
PubMed1988

Necrotizing effect of ethanedimethanesulfonate on spontaneously occurring Leydig cell tumors in old F344 rats.

Thirty 18-month-old male F344/DuCrj rats were divided into the following groups: 10 untreated controls; eight vehicle-injected controls; and 12 ethanedimethanesulfonate (EDS)-injected rats. Untreated controls were killed immediately to check for testicular tumor incidence. In rats of the test group, a 75-mg/kg dose of EDS dissolved in dimethyl sulfoxide:water (1:3) was injected i.p. At intervals of 1, 2, 3, and 10 days after injection, two vehicle-injected control rats and three EDS-injected rats were sacrificed, and the testes were fixed by vascular perfusion. The midsagittal sections of all the fixed testes were examined to determine the incidence of macroscopic Leydig cell tumors, and some tumor tissues of the injection-treated groups were also investigated ultrastructurally. In 28 of 30 animals, a total of 78 Leydig cell tumors could be distinguished. Extensive and severe necrotic alterations accompanying fresh, multiple hemorrhages in early stages and reparative changes in later stages could be observed in a total of 78% of the 32 tumors examined from the EDS-injected group. The tumor cells exhibited ultrastructurally degenerative changes such as chromatin condensation and cytoplasmic vacuolation from 1 day after EDS injection. Therefore, EDS may be a necrotic agent for rat Leydig cell tumor.

Animals↗
PubMed1988

Immunohistochemical demonstration of vasopressin nerve fibers in the cerebral artery.

Vasopressin-immunoreactive nerve fibers were demonstrated in the cerebral pial arteries by peroxidase immunohistochemistry. In the large pial artery (proximal part of the middle cerebral artery), they ran longitudinally to the long axis of the vessel. They ran in a spiral pattern in the distal part of the middle cerebral artery. Even in small arteries, vasopressin nerve fibers were found arranged in a longitudinal fashion. The present morphological data suggest that vasopressin nerve fibers in the cerebral artery may play a role in cerebral circulation.

Animals↗
PubMed1988

The mechanism of discordant xenograft rejection.

The mechanism of discordant xenograft rejection using the guinea pig-to-rat heart graft model was studied. In this model, we found that (A) Rejection occurred rapidly, in 17.5 +/- 8.3 min (mean +/- SD) (n = 8). (B) The graft survived longer when the recipient rat was pretreated with cobra venom facter (CVF). (C) Complement hemolytic titers in serum showed significant reduction of C3 in rejection without consumption of C4 and C2, suggesting complement activation through the alternative pathway. (D) No natural antibodies were detected in this combination. Complement-dependent cytotoxicity (CDC) titer, and hemagglutination (HA) titer were lower than x1. (E) Histological examination of the rejected heart xenograft revealed a large area of myocytolysis without interstitial cellular infiltration. (F) In vitro experiments showed that rat complement attacked guinea pig erythrocytes (Egp) via the alternative pathway. These findings indicate that rejection in this discordant xenograft model of guinea pig-to-rat was caused by primary activation of complement via the alternative pathway.

Animals↗
PubMed1988

Autotransplantation of the superior cervical ganglion into the brain. A possible therapy for Parkinson's disease.

The superior cervical ganglion (SCG) of rats was transplanted into their own parietal cortex. Four weeks after implantation, catecholamine histofluorescence revealed many transplanted catecholamine cells in the cortex. However, no fibers extended from the transplanted tissue to the cerebral cortex. In a second group of rats which had been pretreated with 6-hydroxydopamine (a specific neurotoxin to the catecholamine neuron), some showed extension of catecholamine fibers to the cerebral cortex. To simulate an animal model of Parkinson's disease, MPTP (1-methyl-4-phenyl-1,2,5,6-tetrahydropyridine) was administered to five monkeys. Two weeks after MPTP administration, dopamine terminals in the caudate nucleus disappeared. After autotransplantation of the SCG into the caudate nucleus of these monkeys, many of the transplanted SCG cells extended axons beyond the graft into the caudate nucleus. These results show that transplanted SCG cells survived well in the brain. Under special circumstances, such as a shortage of catecholamine in the brain, implanted SCG cells extended their axons into the brain. It is suggested that autotransplantation of SCG grafts may be a new therapy for Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1988

[Transplantation of the superior cervical ganglion into the brain--a new experimental therapy of Parkinson disease].

To supplement catecholamine deficit in the brain with Parkinson disease, we have aimed to transplant the superior cervical ganglion (SCG), which contains norepinephrine and dopamine, into the brain. 1. Transplantation of SCG into rat cerebral cortex SCG was transplanted into the same rat's parietal cortex. Three weeks after the transplantation, catecholamine histofluorescence revealed many transplanted catecholamine cells in the cortex. However, no fibers extended from the transplanted tissue to the cerebral cortex. Some catecholamine fibers extended to the cerebral cortex where 6-OHDA (a specific neurotoxin to the catecholamine neuron) had been pretreated. 2. Transplantation of SCG into the caudate nucleus of MPTP-induced Parkinson monkey For animal model of Parkinson disease, MPTP (1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine) was administered to 5 monkeys. Tow weeks after MPTP administration, dopamine terminals disappeared in the caudate nucleus. After transplantation of SCG in the same animal, many transplanted SCG cells extended their axons to the caudate nucleus. The present results showed that transplanted SCG cells were well survived in the brain. Under a special circumstance such as shortage of catecholamine in the brain, transplanted SCG cells extended their axons into the brain. It is suggested that the transplantation of SCG can be a new therapy for Parkinson disease.

Animals↗
PubMed1988

[Effects of maternal hyperventilation and oxygen inhalation during labor on fetal blood-gas status].

The effects of maternal hyperventilation and oxygen inhalation on fetal blood-gas status were studied in 54 fetuses, vaginally delivered of mothers without medical and obstetrical complications. The cases were divided into four groups according to MA (maternal arterial) pH and PCO2 values and by respiring either oxygen or room-air as follows. Group N: pH less than 7.5, PCO2 greater than 23 mmHg (normoventilation), without maternal oxygen inhalation, group H: pH greater than 7.5, PCO2 less than 23 mmHg (hyperventilation), without oxygen inhalation, group NO: pH less than 7.5, PCO2 greater than 23 mmHg, with oxygen inhalation and group HO: pH greater than 7.5, PCO2 less than 23 mmHg, with oxygen inhalation. Umbilical venous (UV) PO2 (27.8 mmHg: mean), SO2 (60.8%) and CO2 (oxygen content, 12.4 ml/dl), and umbilical arterial (UA) PO2 (17.9 mmHg), SO2 (35.6%) and CO2 (7.3 ml/dl) values in group H were significantly lower than those in group N. The fetal oxygenation in group HO was similar to that in group N, and the fetal oxygen values in group NO were significantly higher than those in the other groups. The fetuses in groups H and HO tended to respiratory alkalosis. The UV oxygen values had negative correlations with MA pH and positive correlations with the MA PCO2 value in both oxygen and no-oxygen groups. There was no significant correlation between maternal and fetal PCO2 values, and higher fetal oxygen extraction (41%: mean) in group H. These facts suggest that severe maternal respiratory alkalosis due to hyperventilation may lead to a disorder in placental circulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Equilibrium↗
PubMed1987

Microangioarchitecture of the feline spinal cord. Three-dimensional observation of blood vessel corrosion casts by scanning electron microscopy.

The microangioarchitecture of corrosion casts of the cat spinal cord was studied by scanning electron microscopy. On the ventral surface of the spinal cord, the anterior spinal artery and the anterior spinal vein ran parallel along the anterior median fissure. Many central arteries branching from the anterior spinal artery coursed in a wavelike manner in the anterior median fissure. The number of central arteries was lowest in the thoracic spinal cord. Central arteries at some spinal cord levels revealed well-developed anastomoses with other central arteries in the anterior median fissure. These well-developed anastomotic central arteries were frequently observed in the thoracic spinal cord, in which the number of central arteries was lowest. On the dorsal surface of the spinal cord, the posterior spinal vein ran longitudinally at the midline and was drained by circumferential veins and posterior central veins. This vein formed a characteristic anastomotic plexus. Small arterioles (20 microns in diameter) in the spinal parenchyma revealed a ring-like compression at the branching site.

Animals↗
PubMed1987

Regulation of rCBF by intracortical vasoactive intestinal polypeptide-containing neurons. Immunohistochemical and hydrogen clearance study in rats.

The role of intracortical vasoactive intestinal polypeptide (VIP)-containing neurons in the regulation of cortical blood flow was investigated in rats by immunohistochemical and hydrogen clearance methods. Immunohistochemical studies revealed an intimate association between intracortical VIP-containing neurons and small blood vessels. Intracortical injection of a VIP solution (10(-5) M) produced significantly higher blood flow in the treated cortex (mean +/- standard error of the mean: 46.2 +/- 4.0 ml/100 gm/min) than in the untreated cortex (36.9 +/- 2.4 ml/100 gm/min). These data suggest that intracortical VIP-containing neurons produce dilatation of intracortical blood vessels.

Animals↗
PubMed1987

[Ephedrine administration for cesarean section under spinal anesthesia].

Prophylactic ephedrine was administered to healthy parturients undergoing elective cesarean section under spinal anesthesia. The methods of ephedrine administration were as follows: intramuscular injection of 0.3 mg/kg, 15 minutes before the block (20 cases: group M), infusion of 0.02% solution immediately after the block (20 cases: group D), premedication with atropine 0.5 mg and infusion immediately after the block (20 cases: group AD). The mean ephedrine dosage was 18.8 +/- 2.2 gm (SD) in group M, 12.6 +/- 6.2 mg in group D and 5.2 +/- 0.7 mg in group AD, and there were significant differences among the three groups. The base line (a), the minimal postanesthetic (b) and the maximal postpartum systolic blood pressures (c) revealed no significant difference among the three groups, and 'b' was significantly higher than 'a' and lower than 'c' in all groups. Only one case (group M) was transiently hypotensive, while hypertension was not found in any of the subjects. One- and 5-minute Apgar scores were 8 or more in all, and umbilical acid-base values were within normal limits in all of them, though the base deficit in group AD was significantly lower than that in group M. Atropine premedication makes it possible to retrench the ephedrine dosage without any harmful effect on either mother or fetus, and ephedrine infusion makes it easy to cope with changes in maternal blood pressure. Consequently, for healthy parturients receiving elective cesarean section under spinal block, we recommend atropine premedication and minimal infusion of ephedrine immediately following the block.

Adult↗
PubMed1986

The distribution of adrenergic receptors in cerebral blood vessels: an autoradiographic study.

The first morphological evidence of the existence of adrenergic receptors (alpha 1, alpha 2 and beta) within the vascular walls of the central nervous system were presented using the in vitro receptor autoradiographic technique. In the rat pial arteries all three types of adrenergic receptors were demonstrated, whereas the human pial arteries failed to show significant autoradiographic grains of alpha 1 type of adrenergic receptors indicating a considerable inter-species difference in the distribution of adrenergic receptors. alpha 2 and beta receptors in human pial arteries were found not only in the arterial smooth muscle layers but also in the endothelial layers. This suggests a possibility that circulating sympathomimetic agents play some role in controlling the tone or permeability of vascular walls within the central nervous system. A distinct distribution of alpha 1 receptors in cortical layer IV where the vascular plexus was richest may suggest a relation of alpha 1 receptors and blood flow of brain parenchyma.

Animals↗
PubMed1986

Three dimensional observation of the nerve fibers along the cerebral blood vessels.

Three dimensional observation of the nerve fibers along the cerebral blood vessels was investigated by scanning electron microscopy. Electron probe X-ray microanalysis was also performed in the cerebral blood vessels treated with peroxidase-antiperoxidase immunohistochemistry intensified by nickel ammonium sulfate. Nerve fibers (2-8 microns in diameter) formed a plexus on the outer surface of the adventitia. After branching, the nerve fibers penetrated the blood vessel adventitia. Substance P-immunoreactive nerve fibers showed a meshwork pattern in the outer layer of the adventitia, and vasoactive intestinal polypeptide (VIP)-immunoreactive nerve fibers revealed a spiral running pattern in the inner layer of the adventitia. Taken together with previous studies, these findings suggest that substance P nerve fibers in the cerebral arteries may not be related to arterial dilatation or constriction, but VIP nerve fibers may be vasodilative.

Animals↗
PubMed1986

[Intervillous blood-gas status, especially oxygenation during cesarean section].

Intervillous (IV), arterial (MA), and umbilical venous (UV) and arterial (UA) blood-gas values were measured in 36 healthy pregnant women. The patients were divided into three equal groups and underwent elective cesarean sections under spinal block. Oxygen was administered through a nasal cannula (group OL) or a mask (group OH), through group RA received no oxygen inhalation. Mean MAPO2 in each group was 102.0, 213.9 and 482.4 mmHg, respectively. Intervillous PO2 (Mean +/- SD mmHg) was 49.0 +/- 7.1 in group RA, 63.1 +/- 14.5 in group OL, 84.6 +/- 25.2 in group OH, oxygen saturation (%) was 83.2 +/- 6.0, 89.6 +/- 5.5 and 94.3 +/- 2.6, respectively, and oxygen content (CO2: ml/dl) was 12.7 +/- 0.9, 13.7 +/- 1.0 and 14.4 +/- 0.5, severely. There were significant differences in the intervillous oxygen values among the three groups. The intervillous acid-base value in group RA (pH: 7.389 +/- 0.013, PCO2: 33.9 +/- 2.3 mmHg and BD: 4.4 +/- 0.9 m mol/l) showed no significant differences from those of the other groups. Mean UVCO2 was somewhat greater than mean IVCO2 in any group due to the relatively higher oxygen affinity of fetal blood. Both IV and UVPO2 were not so elevated with oxygen inhalation and this was assumed to be due to characteristics of the oxyhemoglobin dissociation curve. The other results produce reliable evidence that placental circulation is not affected by maternal hyperoxia and that an increase in (IV-UA)PO2 facilitates oxygen transfer to the fetus.

Carbon Dioxide↗
PubMed1986

[Neonatal effects of the delivery interval during cesarean section under spinal anesthesia].

The relationships between I-DI (induction to delivery interval) or U-DI (uterine incision to delivery interval) and fetal acid-base status or neonatal clinical condition were studied in 60 healthy parturients undergoing elective cesarean section under spinal anesthesia. The patients were divided into groups, i.e. group A (U-DI less than 90 sec, I-DI greater than 14 min, 18 cases), group B (U-DI less than 90 sec, I-DI greater than 14 min, 12 cases), group C (U-DI greater than 90 sec, I-DI less than 14 min, 15 cases) and group D (U-DI greater than 90 sec, I-DI greater than 14 min, 15 cases). Acid-base values for maternal arterial (MA), umbilical venous (UV) and umbilical arterial blood (UA), and acid-base gradients for (MA-UV) and (UV-UA) in each group were all in the normal range and revealed no significant differences among 4 groups, though U-DI was correlated with UVPCO2, UAPCO2, and (UV-UA) base deficit (r = 0.322, 0.266, -0.256: p less than 0.05). Acid-base states in cases of long and excessively long U-DI (greater than 90 sec and greater than 150 sec, respectively) were more acidotic than those of short U-DI groups (less than 90 sec). Both 1 and 5 minute Apgar scores were 8 or more in all neonates. There was no correlation between I-DI and fetal acid-base values or neonatal clinical conditions. It is conceivable that gentle and careful manipulations of the uterus and fetus rather than shortening of U-DI might be important in preventing against fetal or neonatal depression during cesarean section under spinal block.

Acid-Base Equilibrium↗
PubMed1985

5-Hydroxytryptamine innervation of vessels in the rat cerebral cortex. Immunohistochemical findings and hydrogen clearance study of rCBF.

The role of the central 5-hydroxytryptamine (5-HT) neuron system in cerebral microcirculation of the rat was examined by immunohistochemical and hydrogen clearance methods. Immunohistochemical studies demonstrated 5-HT-immunoreactive nerve fibers along intraparenchymal blood vessels (arterioles, capillaries, and venules). Ultrastructural observation revealed that 5-HT-immunoreactive terminal boutons (0.3 to 1.0 micron in diameter) made contact with the basement membrane of the capillaries. After an intracerebral injection of 5,7-dihydroxytryptamine (5,7-DHT), a neurotoxin to the 5-HT neuron system, no 5-HT-immunoreactive nerve fibers were found around the injection site with immunohistochemical techniques. With the hydrogen clearance method, the 5,7-DHT-injected cortex showed no significant change in regional cerebral blood flow (rCBF) in the presence of normocapnia, but a significant increase in rCBF with hypercapnia, compared with the untreated cortex. These facts strongly suggest that the central 5-HT neuron system has an important role in carbon dioxide reactivity of the cerebral blood vessels.

Animals↗
PubMed1985

[A case of renal cell carcinoma found in traumatic ruptured kidney].

A case of traumatic kidney rupture with pre-existing renal cell carcinoma in a 38-year-old male is reported. Macrohematuria appeared 48 hours after left precordial trauma in a traffic accident. Initial diagnosis at the emergency clinic was 9th rib fracture of his left chest alone and no other injury was recorded. A large mass in left abdomen was palpable at urologic OPD, however, and X-ray examination revealed a non-visualizing left kidney in IVP. After the ECHO, CT and arteriography findings gave an impression of left kidney rupture. Left nephrectomy accompanied by partial colectomy of descending colon by transperitoneal approach was performed 25 days after initial trauma. This delay was mainly due to disagreement of patient for surgical treatment because there were no subjective symptom except microhematuria and subsiding fever after transfer to the urologic section. En bloc removed specimen showed ruptured kidney with adhesiveness laterally to descending colon and harder core portion was found in midst of renal mass. Coronal slice of the specimen exhibited a renal parenchymal tumor with necrotic spots. Pathologic findings were complete kidney rupture in upper pole and clear cell type renal cell tumor was found in mid and lower pole. Also lymph nodes which obtained from left renal pedicle and para aortic margin proved no metastasis of tumor cell. Post operative clinical course was favourable without any recurrence for 15 months after surgery. Clinical incidence of type I and type II kidney trauma with pre-existing neoplastic change is considerably high, but the kidney ruptured case bearing renal cell carcinoma as a core shape is very rare.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

A light and electron microscopic immunohistochemical study of vasoactive intestinal polypeptide- and substance P-containing nerve fibers along the cerebral blood vessels: comparison with aminergic and cholinergic nerve fibers.

Vasoactive intestinal polypeptide (VIP)- and substance P-containing nerve fibers were observed in the cerebral blood vessels using an immunohistochemical technique. VIP-containing nerve fibers distributed in a spiral pattern, similar to that of muscle cells. Under electron microscopic observation, VIP-immunoreactive terminals lay close to a muscle cell in the inner layer of the adventitia. In contrast, substance P-containing nerve fibers showed a meshwork pattern in the outer layer of the adventitia. Using both acetylcholinesterase (AChE) staining and VIP immunohistochemistry, AChE-positive and VIP-immunoreactive nerve fibers revealed almost the same distribution in the same specimen. The present data suggest that VIP-containing nerve fibers may play a role in the smooth muscle control of the blood vessels, whereas substance P-containing nerve fibers may not take part in muscle control.

Animals↗